Dr. William Harris is a research professor at the Sanford School of Medicine in South Dakota, and an established authority on omega-3 fats. He’s a prolific researcher and has published a number of articles in some of the major peer-reviewed scientific journals.

Here, Dr. Harris shares his insights on the health benefits of omega-3 fats, and an innovative new way to determine whether you’re getting enough of this valuable nutrient.

Dr. Mercola's Comments:

Dr. William Harris earned his PhD in nutrition from the University of Minnesota back in the 70s, and did a post-doctoral fellowship with one of the leading omega-3 experts in the world, Dr. Bill Connor in Portland, Oregon.

"One of the first assignments Dr. Connor gave as a new PhD was to figure out what salmon oil does to blood cholesterol level in people, because we really didn't know," Dr. Harris says. "… I did some of my original studies there, and we found that the omega-3 fats in fish oil lowered triglyceride levels in the blood. We thought we were looking for cholesterol effect, but we saw a triglyceride effect. It's a different blood lipid.

From that point, we started to learn about the Eskimo studies that had been done by Dyeberg and Bang in Greenland and how the high omega-3 diet of the Eskimo was apparently what protected them from heart attacks... It has just snowballed, since then."

Indeed, today, we know that omega-3 has many profound health benefits that go far beyond the lowering of triglycerides, although the heart health benefits of omega-3 are the most well-established and commonly accepted. Even the FDA allows claims for omega-3 for heart disease.

Did You Know? Your Omega-3 Levels Can Now Be Measured

Yes, you can actually measure the omega-3 level in your blood, which will also give you information about your risk for heart disease. Dr. Harris' research led to the development of an assay that measures your omega-3 level, which is referred to as the "omega-3 index."

"We measure the omega-3 level in red blood cells as a reflection of the omega-3 levels in all the tissues," Dr. Harris explains. "We then use that to help people figure out if their omega-3 levels are too low. We really haven't seen [levels that are] too high, so that's apparently not a problem."

The red blood cell as a marker for the omega-3 fat level is comparable to a test used for diabetes, which measures the hemoglobin A1c, or glycosylated hemoglobin. Using the red blood cells can give you a good indication of how well you've controlled your diabetes in the past three months, because that's the typical life span of your red blood cells.

The omega-3 assay does the same thing and shows you your omega-3 status based on your omega-3 consumption over the last three months. So it's not easily influenced by a large fish meal the night before the test.

What's the Ideal Omega-3 Level?

Dr. Harris' omega-3 assay can be used as a helpful gauge of your heart disease risk. In case control studies, blood samples were obtained from people admitted to the hospital to evaluate heart attack risk based on their omega-3 levels.

"We looked at the difference in omega-3 levels and found that those who have heart attacks are much more likely to have a low level [of omega-3]. A low level meaning under 4 percent… and very unlikely to have an omega-3 level above the eight percent range where we think it's good" Dr. Harris says.

The omega-3 index is expressed as the amount of omega-3 in the red blood cell as a percentage. The omega-3s typically run from about two to 10 percent. According to Dr. Harris, the current belief is that a level:

Below four percent puts you at high risk for heart attack

Between four and eight percent puts you at intermediate risk

Above eight percent is considered the target value for low risk

Measuring Your Trans Fat Levels

Another piece of information that can be found in your fatty acid profileis your level of trans fats (omega-6 and omega-9)—the bad fats that we now know are responsible for the majority of cardiovascular problems that have long been blamed on saturated fats.

"Of course trans fats are the ones that are produced from industrial treatment of vegetable oils to make margarines and shortenings. They're pervasive in baked goods and fried foods," Dr. Harris explains. "We can measure that level in the red blood cell as well. Although there is not nearly as much data that will allow to us say—like we have for the omega-3 index—eight percent is good; four percent is bad. We're not quite there with the trans (fats) yet but we are developing those metrics.

We can say that, if a doctor has a patient, or an individual wants to know [their levels] themselves, they can do an omega trans test… They get their trans level and then they change their diet… If the patient or the individual… actually does reduce their intake, you'll see it… So it's a good indicator of following a healthier overall diet."

The Relationship Between Omega-3 Levels and Aging

In addition to evaluating heart disease risk, Dr. Harris has also looked at the relationship between omega-3 levels and cellular aging. It's well-known that although the clock on the wall may tick at the same speed for all of us, our biological clocks move at different speeds depending on a number of lifestyle factors, which includes omega-3 consumption.

A test that is being increasingly used to measure cellular aging involves measuring the length of your telomeres—a section of your DNA that's in every cell of your body. Based on what I've learned from experts within the anti-aging field, telomeres appear to be the most accurate biological clock we have. A telomere is about 15,000 bases long at the moment of conception in the womb. Immediately after conception your cells begin to divide, and your telomeres shorten each time the cell divides. Once your telomeres have been reduced to about 5,000 bases, you essentially can die of old age.

"If we look over a five year span of time, we can measure the loss of telomeres in the DNA," Dr. Harris explains. "The more telomeres that are lost, the faster the cell is aging… We have the marker then, of cellular aging."

After comparing the omega-3 levels of the participants with how fast their cells aged over five years, they discovered that, again, those who have an omega-3 index of less than four percent age much faster than those with indexes above eight percent. Therefore, your omega-3 index may also be an effective marker of your rate of aging.

One of the central anti-aging theories relating to telomeres, as of right now, is to try to activate telomerase, to actually increase the telomeres' length and essentially reverse aging. Interestingly enough, according to Dr. Harris, omega-3 fats may play a role in activating telomerase!

"In the same study that we looked at the rate of aging in the cells, we… [also] did body counts; we measured how many people died, and found that those people who had the higher omega-3 levels died at a slower rate, or were less likely to die within the study period than the people who had low omega-3s," Dr. Harris says. "So that fits with the idea that the rate of telomere changing correlates with the rate of death. It's just an important factor."

Although this research is preliminary, I would suggest that optimizing your omega-3 levels above eight percent would be a good strategy if you're interested in delaying aging. After all, you have nothing to lose and a lot to gain by doing so, since omega-3 has proven to be extremely important for your health in so many respects.

The Many Health Benefits of Omega-3 Fats

The cardiovascular benefits of animal-based omega-3 fats are quite well-established, and include:

Antiarrhythmic: counteracting or preventing cardiac arrhythmia

Antiatherosclerotic: preventing fatty deposits and fibrosis of the inner layer of your arteries from forming

Improves endothelial function: a major factor in promoting the growth of new blood vessels

More recent findings indicate that omega-3 may play an important role in brain health, potentially stalling the development of dementia. Previous research has already shown it can be quite useful in the treatment of depression. However, there is a caveat… More than likely, especially for the prevention of more serious brain diseases like Alzheimer's, you'd have to maintain optimal omega-3 levels for a good portion of your life. Waiting until you're in your mid-60's may be, as Dr. Harris says, "too little, too late" to have any major impact on the trajectory of your mental functioning.

Ideally, everyone really needs to aim for a lifetime of high omega-3 levels, to reap all the health benefits that it has to offer.

Another active area of research is omega-3's impact on joint health, arthritis, and inflammation. Omega-3 appears to be anti-inflammatory in a very general way, which seems to be good for most people in general. For more information about the various health benefits of omega-3 fat, please review the following links:

Surprising Findings on the Side Effects of Omega-3 Fats

According to Dr. Harris' research, there does not appear to be an upper limit, above which you will experience adverse effects, when you take animal-based omega-3 fats. This is somewhat surprising. Oftentimes, there's a price to pay for consuming too much of any particular nutrient, even if it's otherwise considered healthy. But so far, he's not found an upper limit, above which omega-3 turns detrimental.

"Japan is a great example because… the Japanese live on average four years longer than we [Americans] do, and they have omega-3 levels that are twice as high as ours for their whole life; not just when they decide to take fish oil, because fish is just a big part of their diet.

The Japanese don't seem to have any adverse effect to having omega-3 levels that are double ours. They just benefit… [T]hey have very little heart disease and live four years longer on average, in spite of the fact that they smoke more than we do, and… have more hypertension… In spite of those two problems, they still live longer. They still have less coronary disease than we do. I think that's an omega-3 related effect."

According to Dr. Harris, the average Japanese omega-3 level is around 9.5 to 10 percent. The highest level he's ever seen was 20 percent. That said, it's worth to consider that there may be a difference between getting high levels of omega-3 from regularly consuming a whole food like fish, compared to swallowing high amounts of concentrated omega-3 in the form of a supplement. Whenever you're dealing with a supplement, there's the potential that the fats may be damaged by oxidation.

Dr. Harris agrees on this point, stating that, ideally, you'd want to get your omega-3 from fish. However, virtually all fish are now highly contaminated with toxins, such as mercury, PCB's, and radioactive substances, which is why I personally do not recommend fish as your primary source of omega-3. In fact, I don't even recommend using fish oil supplements anymore, for a number of reasons.

Why I Recommend Krill Oil Instead of Fish Oil

Aside from higher potential for contamination, fish oil supplements also have a higher risk of suffering oxidation damage and becoming rancid, both during the processing and after you open the bottle. Dr. Rudi Moerck expounded on these risks at great length in a previous interview.

Krill oil would also be highly unstable if it wasn't for the fact that it contains the exceptionally potent antioxidant astaxanthin, which keeps it safe from oxidative damage. In fact, in tests performed by Dr. Moerck, the krill oil remained undamaged after being exposed to a steady flow of oxygen for 190 hours, compared to fish oil, which went rancid after just one hour!

That makes krill oil nearly 200 times more resistant to oxidative damage compared to fish oil. Additionally, as Dr. Harris confirms, krill oil is also more potent gram for gram, as its absorption rate is much higher than fish oil.

"You actually get more omega-3 from eating krill," he says.

According to his research, you get somewhere between 25 to 50 percent more omega-3 per milligram when you take krill oil compared to fish oil.

Can You Receive the Same Benefits from a Plant-Based Omega-3?

It's important to realize that not all omega-3 fats are the same. Some people opt to exclude animal-based products from their diet, which can have a detrimental effect on their omega-3 status, even if they include plant-based omega-3's. According to Dr. Harris, you will not get the health benefits discussed so far from plant-based omega-3, which is primarily ALA. He explains:

"[T]he longer chain EPA and DHA omega-3s can be made from the short chain alpha linolenic ALA, but it's with great inefficiency… EPA will go up a little bit. Maybe if you really increase the ALA intake, you might get a half a percent increase in EPA but you… might get a decrease in DHA so that there is no effect on the omega-3 index... We've looked, and seen that people who really go out of their way to increase their ALA intake do not a get a bump in the omega-3 index."

This is important, as the omega-3 assay can be used as a marker for both heart disease risk and cellular aging.

More Information

"There is a laboratory that I'm now associated with called Health Diagnostic Laboratory," Dr. Harris says. "That's in Richmond, Virginia. It's abbreviated HDL, which is nice because that's the good lipoprotein. HDL is good.

At HDL, they're beginning to offer this test to clinicians as part of the panel that they're giving. They have brought my test into this lab. They're scaling it up much bigger than what I have been doing in my research lab. So HDL is a place that physicians can order the test for their patients in that context."

Disclaimer: The entire contents of this website are based upon the opinions of Dr. Mercola, unless otherwise noted. Individual articles are based upon the opinions of the respective author, who retains copyright as marked. The information on this website is not intended to replace a one-on-one relationship with a qualified health care professional and is not intended as medical advice. It is intended as a sharing of knowledge and information from the research and experience of Dr. Mercola and his community. Dr. Mercola encourages you to make your own health care decisions based upon your research and in partnership with a qualified health care professional. If you are pregnant, nursing, taking medication, or have a medical condition, consult your health care professional before using products based on this content.

If you want to use an article on your site please click here. This content may be copied in full, with copyright, contact, creation and information intact, without specific permission, when used only in a not-for-profit format. If any other use is desired, permission in writing from Dr. Mercola is required.

Disclaimer: The entire contents of this website are based upon the opinions of Dr. Mercola, unless otherwise noted. Individual articles are based upon the opinions of the respective author, who retains copyright as marked. The information on this website is not intended to replace a one-on-one relationship with a qualified health care professional and is not intended as medical advice. It is intended as a sharing of knowledge and information from the research and experience of Dr. Mercola and his community. Dr. Mercola encourages you to make your own health care decisions based upon your research and in partnership with a qualified health care professional. If you are pregnant, nursing, taking medication, or have a medical condition, consult your health care professional before using products based on this content.

If you want to use an article on your site please click here. This content may be copied in full, with copyright, contact, creation and information intact, without specific permission, when used only in a not-for-profit format. If any other use is desired, permission in writing from Dr. Mercola is required.